Mary Eliza Mahoney, born in 1845 in Dorchester, Massachusetts, was the first African American to study and work as a professionally trained nurse in the United States. In 1879, Mahoney was the first African American to graduate from an American school of nursing.

Mahoney knew early on that she wanted to become a nurse; possibly due to seeing immediate emergence of nurses during the American Civil War. Black women in the 19th century often had a difficult time becoming trained and licensed nurses. Nursing schools in the South rejected applications from African American women, whereas in the North, though the opportunity was still severely limited, African Americans had a greater chance at acceptance into training and graduate programs. As soon as the New England Hospital for Women and Children was created, she began to show an interest in nursing at age 18. Mahoney was admitted into a 16-month program at the (now the Dimock Community Health Center) at the age of 33, alongside 39 other students, in 1878. Out of a class of 40 students, she and two other white women were the only ones to receive their degree. It is presumed that the administration accepted Mahoney, despite not meeting the age criteria (21-31), because of her connection to the hospital through prior work as a cook, maid, and washerwoman there when she was 18 years old.

Mahoney's training required she spend at least one year in the hospital's various wards to gain universal nursing knowledge. The work within the program was intensive and consisted of long days with a 5:30 A.M. to 9:30 P.M. shift, requiring Mahoney to attend lectures and lessons to educate herself through instruction of doctors in the ward. Outside of the lectures, students were taught many important bedside procedures such as taking vital signs and bandaging. In addition, Mahoney worked for several months as a private-duty nurse. Three quarters of the program consisted of the nurses working within a surgical, maternity or medical ward with six patients they were responsible for. The last two months of the extensive 16-month long program required the nurses to use their newfound knowledge and skills in environments they were not accustomed to such as hospitals or private family homes. After completing the requirements for a very rigorous program, Mahoney graduated in 1879 as a registered nurse alongside 3 other colleagues — the first Black woman to do so in the United States.

After receiving her nursing diploma, Mahoney worked for many years as a private care nurse, earning a distinguished reputation. Of the many goals that Mahoney had hoped of achieving, one was to change the way patients and families thought of minority nurses. Being African American in a predominantly white society, she often experienced discrimination as an African American woman. She believed that all people should have the opportunity to chase their dreams without racial discrimination.

In 1896, Mahoney became one of the original members of the then-predominantly white Nurses Associated Alumnae of the United States and Canada (NAAUSC), which later became the American Nurses Association (ANA). In the early 1900s, the NAAUSC did not welcome African American nurses into their association. In response, Mahoney co-founded a new, more welcoming association, with help of Martha Minerva Franklin and Adah B. Thoms. In 1908, she became co-founder of the National Association of Colored Graduate Nurses (NACGN).

From 1911 to 1912, Mahoney served as director of the Howard Colored Orphan Asylum for Black children in Kings Park, Long Island, New York. The asylum served as a home for freed colored children and the colored elderly. This institution was run by African Americans. Here, Mary Eliza Mahoney finished her career, helping people and using her knowledge however she knew best.